Starting, we can all agree we don’t like the winter (or at least the cold for that matter), so when we read articles published by other sites stating that we don’t have to warm up our cars, we usually chime back with “Well I’m not warming it up for the car, I’m warming it up for me!”
We agree, but let’s dive into why it’s not needed as far as the car is concerned, barring any legal reasons.
To understand why this was a practice when cars with carburetors were still running the roads, we must understand gasoline (we’ll touch into diesel later) and how it reacts to colder temperatures. First, the flashpoint (temperature in which a liquid gives off ignitable vapor) of gasoline is -45F. The closer the temperature is to that number, the harder it is for gasoline to produce vapor. Since gasoline motors run on gas vapor when the temperature is below freezing, the engine will require more gas for there to be more vapors to ignite and start the engine. This was the purpose of the choke used on carbureted vehicles then and most small engines today. Once the engine starts reaching operating temperature, the gasoline will produce more vapor and thus you can start introducing more air (removing choke).
Cars today do all this automatically by controlling the fuel injectors pulse, the air allowed in and change running parameters to match the outside conditions. Therefore, you can drive the car 30 seconds once you let the oil flow around the engine and transmission. Now the reason why articles have been circulating to drive cars in 30 seconds is primarily the premise of what was discussed earlier. A car will warm up faster when an engine is working under load. When you’re driving the vehicle, the engine is working to move every part of the car forward including you and your latte or tea. Since this requires more fuel than at idle, it will warm up faster than if it was running with no load. When a car reaches operating temperature, most emission systems will become more efficient in reducing harmful exhaust gases as well as the car computer will start to adjust fuel closer to optimum efficiency.
With that being said, this doesn’t touch on compression-based engines (Diesel) and their reactivity to the cold. Remember earlier we said that gasoline engines require vapor to run? That’s because they’re ignition-based engines where they require a spark plug to ignite the fuel. Diesel engines do not require spark plugs since they have a higher compression ratio and utilize diesel fuel’s auto-ignition temperature which is 410F. To achieve this temperature, the engines have glow plugs. These glow plugs will heat the internal temperature of the cylinder to self-ignite the diesel fuel.
Now, to fully compare apples to apples, a diesel engine of the same size to a gasoline counterpart will warm up in about the same time. The reason diesel engines in a common context like the Duramax, Powerstroke, Cummins, etc. take longer to warm up is naturally just their size. Larger engines take longer to warm up, due of course to the heat of fuel detonation to permeate fully through a larger engine block and larger cooling system. Another reason is diesel engines have turbochargers that are lubricated by the engine oil. To promote longevity of the turbo, you’ll want the turbo bearings to be lubricated with warm oil and to have the turbo warm up before you put the engine under load. The same goes for shutting down, you’ll want to idle after a highway run for about 3-5 minutes to cool off the turbo.If you like detailed articles such as what you just read, be sure to support our Patreon page for more informational articles, tips and tricks, and tool reviews and check us out on Youtube @ Motorly.